如何编写一个 returns 两个文档之间的余弦相似度的方法

Question

我正在写一个 returns 两个文档之间的余弦相似度的方法。使用 sklearn CountVectorizer() 我试过了

from sklearn.feature_extraction.text import CountVectorizer
from sklearn.metrics.pairwise import cosine_similarity

def doc_cos_similar(doc1:str, doc2:str) -> float:
  vectorizer= CountVectorizer()
  doc1="Good morning"
  doc2="Good evening"
  documents = [doc1, doc2]
  count_vectorizer = CountVectorizer()
  sparse_matrix = count_vectorizer.fit_transform(documents)
  doc_term_matrix = sparse_matrix.todense()
  return doc_term_matrix

#输入

doc1="Good morning"
doc2="Good afternoon"

输出应该是 0.60（类似的东西）

但是输出是一个

matrix([[0, 1, 1], [1, 1, 0]])

Answer 1

你可以试试这个：

from nltk.corpus import stopwords
from nltk.tokenize import word_tokenize

# X = input("Enter first string: ").lower()
# Y = input("Enter second string: ").lower()
X ="Good morning! Welcome"
Y ="Good evening! Welcome"

# tokenization
X_list = word_tokenize(X)
Y_list = word_tokenize(Y)

# sw contains the list of stopwords
sw = stopwords.words('english')
l1 =[];l2 =[]

# remove stop words from the string
X_set = {w for w in X_list if not w in sw}
Y_set = {w for w in Y_list if not w in sw}

# form a set containing keywords of both strings
rvector = X_set.union(Y_set)
for w in rvector:
  if w in X_set: l1.append(1) # create a vector
  else: l1.append(0)
  if w in Y_set: l2.append(1)
  else: l2.append(0)
c = 0

# cosine formula
for i in range(len(rvector)):
  c+= l1[i]*l2[i]
cosine = c / float((sum(l1)*sum(l2))**0.5)
print("similarity: ", cosine)

Answer 2

你快到了。

cosine_similarity(doc_term_matrix) returns

array([[1. , 0.5],
       [0.5, 1. ]])

所以你可以使用cosine_similarity(doc_term_matrix)[0][1]（或[1][0]，因为余弦是对称的所以没关系）。

P.S。您应该将 doc1 和 doc2 作为参数传递，而不是对它们进行硬编码。

如何编写一个 returns 两个文档之间的余弦相似度的方法

How to write a method that returns cosine similarity between two documents

python-3.x

nlp

cosine-similarity

countvectorizer